Fluid switching device



6 R. w. NICKELSON 3,360,625

FLUID SWITCHING DEVICE Filed Sept; 12, 1966 5 Sheets-Sheet 1 Fl I T FIGZINVENTOR ROBERT w. NICKELSON BY J'Eumm ATTORNEYS Dec. 26, 1967 I R. w.NICKELSON 3,360,625

FLUID SWITCHING DEVICE Filed Sept. 12, 1966 5 Sheets-Sheet 2 54 a+ 54F167 a 5| FIGS? I I I 55 ll 5| /6O l w 56 1 65 56- ,eo :5: fi m 62 74 7363 734 If i I 63 77 52 77 J52 i 76 If? 76 INVENTOR ROBERT W. NICKELSONBY gm AM/mm fm ATTORNEYS Dec. 26, 1967 R. w. NICKELSON 3,360,625

FLUID SWITCHING DEVICE Filed Sept. 12, 1966 5 Sheets-Sheet 5 FlGIOFIGLIII 84 0 INVENTOR ROBERT w. NICKELSON BY 1 Mi ATTORNEYS UnitedStates Patent 3,360,625 FLUID SWITCHING DEVICE Robert W. Nickelson, ElkGrove Village, Ill., assignor to Beltone Electronics Corporation, acorporation of Illinois Filed Sept. 12, 1966, Ser. No. 578,597 6 Claims.(Cl. 200--152) 7 ABSTRACT OF THE DISCLOSURE Anelectrical switch having afluid switching element mounted within a molded plastic housing. Theswitching element comprises a pair of spaced-apart contacts positionedinside an elastically deformable container which is partially filledwith an electrically conductive, nonwetting fluid (such as mercury). Apair of actuating membersarefastened on opposite sides of the deformablecontainer such that, when the members are pressed together, the fluidpassageway through the container is constricted, thereby separating thefluid into spaced-apart physical segments and opening the circuit paththrough the fluid. When the actuating members are moved apart, thepassageway is forcefully opened-to again create a fluid circuit path.Oneof the actuating members may be spring loaded to hold the switchin anormally open or normally closed position.- Y

Background and summary of the invention This invention relates to animproved electrical switchingarrangement wherein electrical connectionsare established through an electrically conductive fluid such asmercury.

U.S. Patent No. 3,177,327 which issued to Erwin M. Weiss on Apr. 6,1965, discloses a fluid switch construction employing a sealed,deformable container partially filled with an electrically conductive,non-wetting fluid. Switching is accomplished by deforming the vessel toconstrict a fluid-holding passage between the terminals of the switch.At the point of constriction, the fluid physically separates to open theelectrical circuit path. The operation of this switch is based upon theinteraction between surface tension forces and the internal pressureforces within the deformable container.

The fluid switch disclosed in the Weiss patent possesses numeroussignificant advantages. In particular, undesirable contact openings andclosures due to contact bounce (which results from the elastic collisionwhich takes place between the contacts in a mechanical switching device)are eliminated. Furthermore, the sealed fluid switch described in theabove patent does not suffer from the eifects of contactdeterioration-or the formation of contaminating films between thecontacts.

After extended use, such fluid switches are subject to sticking; thatis, the interior surfaces of the fluid-holding envelope, when pressedtogether as the envelope is constricte'd, may adhere to one another,maintaining an open condition between the electrical terminals of theswitch even after the constricting force is removed.

It is accordingly a first object of the present invention to eliminatesticking in a fluid switch.

It is a more general object of the present invention to provide a newand improved fluid switch construction which is simple and inexpensive,yet which provides improved performance and great durability.

In a piincipal aspect, the present invention takes the form of a fluidswitch including a pair of spaced-apart contact terminals and anelastically deformable, hollow envelope which defines. a passagewaybetween these terminals. The passageway is at least partially filledwith an electrically conductive fluid which is non-wetting with respectto the interior surface of the envelope. In accordance with a feature ofthe invention, first and second actuating members are fastened to theenvelope on opposing sides of the passageway and means are employed formoving at least one of these members relative to the other to constrictthe passageway when the members are spaced closely together in order toseparate the fluid into noncontacting physical segments. When themembers are moved apart, the passageway is forcefully opened, unitingthe fluid segments, and creating a low impedance electrical connectionthrough the fluid between the contact terminals. Because the actuatingmembers are rigidly affixed to the envelope, the force which is appliedto separate the actuating members serves to break the adhesion betweenthe interior surfaces of the passage. In a preferred, normally closedembodiment of the invention,

I the envelope is mounted, a portion of the surface of the envelopebeing adhesively aifixed to the interior surface of the housing suchthat this portion of the housing forms one of the actuating members. Acontrol, extending through the housing, isthen employed for moving thesecond actuating member, which is attached to the envelope at a pointopposite from the point where the housingis aflixed.

Brief description of the drawings These and other objects, features andadvantages of the present invention may be more clearly understoodthrough a consideration ofthe following detailed description. In thecourse of this description, reference will frequently be made to theattached drawings in which:

FIGURE 1 is a side elevational view taken partially in cross-section andillustrating the operation of the invention;

FIGURE 2 is a side elevational view of the switch shown in FIGURE 1 withthe interior passageway constricted;

FIGURE 3 is a cross-sectional view taken along the line 3-3 of FIGURE 1;

FIGURE 4 is a side cross-sectional view taken along the line 4-4 ofFIGURE 2;

FIGURE 5 is a perspective view of a preferred embodiment of theinvention shown with a portion of the housing cover broken away to showthe interior details of the switch construction;

FIGURE 6 is a side cross-sectional View of the switch shown inperspective in FIGURE 5 in the normally closed position;

FIGURE 7 is an end cross-sectional view of the switch shown taken alongthe line 7-7 of FIGURE 6;

FIGURE 8 is a side cross-sectional view of the switch shown inperspective in FIGURE 5 in the normally open position;

FIGURE 9 is an end cross-sectional view of the switch taken along theline 99 of FIGURE 8;

FIGURE 10 is a side cross-sectional view of a second embodiment of theinvention shown in its normally closed position;

FIGURE 11 is an end cross-sectional view taken along the line II-l1 ofFIGURE 10;

1 FIGURE 12 is a side, cross-sectional view of the second position; and,

FIGURE 13 is an end, cross-sectional view taken along the line 13-.13 ofFIGURE 12.

Description of the preferred embodiments The operation of the inventionis illustrated by FIG- URES 1 through 4 of the drawings. FIGURE 1 showsan elastically deformable, tubular envelope, shown generally at 21,which includes an interior, hollow region at least partially filled withan electrically conductive, non-wetting fluid (such as mercury)illustrated at 23. The ends of the tubular envelope are sealed by themetallic end caps 25 and 27. The envelope 21 includes upper and lowerprojecti-ons 31 and 33 respectively. As best seen in FIGURES 3 and 4, anactuating wire 35 passes through the projection 31 and extends outwardlyon both sides of the envelope 21. The lower projection 33 is cementedinto a notch 37 cut into the base surface 40. Coil springs 41 and 42 areshown projecting from the ends of actuating wire 35 to the base surface40.

The springs 41 and 42 hold the actuating wire 35 in spaced relation fromthe base surface 40 to complete an electrical connection between themetallic end caps 25 and 27 through the fluid 23. This circuit path maybe opened by depressing the actuating wire 35 to constrict thepassageway within envelope 21, thereby separating the liquid 23 intospaced apart physical sections 23a and 23b as shown in FIGURE 2. Asdepicted by FIGURE 4, the actuating wire 31 insures that the passagewaywithin envelope 21 is constricted across its entire width. Thecompressed springs 41 and 42 insure that the circuit connection will beagain closed (that is, the constriction in the fluid passageway will beremoved) when the downwardly directed actuating force is removed fromthe actuating wire 31. Since the opposing sides of the envelope 21 areaflixed respectively to the actuating wire 31 and to the base surface40, any tendency of the inner surfaces of the envelope to adheretogether is overcome.

A preferred embodiment of the invention is shown in the perspective viewof FIGURE 5, an exterior portion of the switch being cut away toillustrate its inner details. The embodiment shown in FIGURE includes abase section, indicated generally at 52, upon which a cover 51 ismounted. A push button 54 extends upwardly through an opening 55 incover 51. The bottom surface of push button 54 bears against anactuating wire, indicated generally at 60, which passes through anupwardly projecting portion 62 of a fluid-holding envelope 63. The endsof the actuating wire 60 nest within a spring member 65 which serves tohold wire 60 in an upwardly raised position. Each end of thefluid-holding envelope 63 is terminated by a metallic end cap of thetype shown generally at 67 in FIGURE 5 which includes an outwardlyextending terminal stud 68 which is welded to a switch contact, one ofwhich is shown generally at 70. Contact 71 forms the remaining terminalfor this normally closed switch.

The switch shown in FIGURE 5 is operated by depressing the button 54which moves the wire actuator 60 downward, constricting the fluidpassageway within the envelope 63, separating the conductive fluidtherein into two physical segments, and opening the switch. Whenpressure is removed from button 54, the shaped metal spring 65 pressesupward on the actuator 60 to again close the circuit path through thefluid.

The details of the switch shown in prospective in FIG- URE 5 are shownmore clearly in the cross-sectional views of FIGURES 6 through 9. Thebase section 52 includes a pair of longitudinal pedestals 73 and 74(best seen in FIG- URES 7 and 9) upon which the spring 65 rests. Thelongitudinal pedestals 73 and 75 also serve to prevent motion of thecover 51 with respect to the base 52 after the two have been joined.

A projection 75 extends downwardly from the undersurface of envelope 63and, as seen in FIGURES 7 and 9,

is sandwiched between a pair of raised ridges 76 and 77. The projection75 is thus cemented to base section 52 such that, as the actuating wire60 is urged upwardly by spring 65, any adhesion which may exist betweenthe abutting interior surfaces of envelope 63 is broken.

FIGURES 10 through 13 of the drawings show a normally open fluid switchwhich embodies the principles of the invention. As shown in FIGURE 10,theswitch comprises a base section indicated generally at 81, a covershown generally at 82, and includes a pushbutton shown at 84. Thepushbutton 84 passes through a circular opening and a bezel 86 which isafiixed to the upper surface of the cover 82.

The switch shown in FIGURES 10 through 13 includes a fluid switchcartridge of the type discussed in conjunction with FIGURES 1 through 9which includes a deformable, elastic envelope indicated generally at 88,a pair of metallic end caps 89 and 90 and centrally located upper andlower projections 91 and 92. An actuating Wire 94 extends through thelower projection 92 and nests Within a metal shaped spring 96. A pair ofterminal contacts 97 and 98 extend downwardly through the base section81 and are welded to the metallic end caps 90 and 89 respectively.

As best seen in FIGURES 11 and 13, the button 84 includes a bifurcatedbottom section comprising the downwardly extending arms 101 and 102. Thearms 101 and 102 extend through openings 103 and 104 respectively in thecover 82 and engage with the wire actuator 94. The upper projection 91on the envelope 88 is cemented into a notch 107 defined between a pairof projections 111 and 112 which extend downwardly from the cover 82.The base section 81 includes a notch 114 centrally located on its insidesurface to permit downward movement of the wire holding projections 92on envelope 88.

With no pressure applied to the button 84, the spring 96 bears upwardlyon the actuating wire 94, constricting the fluid passage within envelope91 and forcing the button 84 upward. In this condition, the fluid withinthe envelope 88 is broken into two separate physical segments preventingcurrent flow between the terminal 97 and 98.

When the button 84 is depressed, however, the arms 101 and 102 beardownward on the Wire actuator 94, re-

moving the constriction from the tubular envelope 88 to. create a lowimpedance electrical connection between the terminals 97 and 98.

It is to be understood that the embodiments of the invention which havebeen described are merely illustrative of application of the principlesof the invention. Numerous modifications may be made by those skilled inthe art without departing from the true spirit and scope of theinvention.

What is claimed is:

1. In combination,

a pair of spaced apart contact terminals,

an elastically deformable, hollow envelope defining a passageway betweensaid terminals, said passageway being at least partially filled with anelectrically conductive fluid which is non-wetting with respect to theinterior surface of said envelope,

first and second actuating members fastened to said envelope on opposingsides of said passageway,

and means for moving at least one of said members relative to the otherof said members between first and second positions, said members in saidfirst position being spaced closely together to constrict saidpassageway to separate said fluid into non-contacting physical segmentsand said members in said second position being spaced apart to open saidpassageway to create a low impedance electrical connection through saidfluid between said first and second terminals.

2. A combination as set forth in claim 1 including spring means fornormally holding said members in said first position.

3. A combination as set forth in claim 1 including spring means fornormally holding said members in said second position.

4. A combination as set forth in claim 1 including a housing for saidenvelope and wherein said first actuating member constitutes a portionof said housing.

5. A combination as set forth in claim 4 including a control extendingthrough said housing for moving said second member.

6. A combination as set forth in claim 4 wherein a portion of thesurface of said envelope is adhesively aflixed to a portion of theexterior surface of said housing.

5 References Cited UNITED STATES PATENTS 3,177,327 4/1965 Weiss 200-152ROBERT K. SCHAEFER, Primary Examiner. 10 H. HOHAUSER, AssistantExaminer.

1. IN COMBINATION, A PAIR OF SPACED APART CONTACT TERMINALS, ANELASTICALLY DEFORMABLE, HOLLOW ENVELOPE DEFINING A PASSAGEWAY BETWEENSAID TERMINALS, SAID PASSAGEWAY BEING AT LEAST PARTIALLY FILLED WITH ANELECTRICALLY CONDUCTIVE FLUID WHICH IS NON-WETTING WITH RESPECT TO THEINTERIOR SURFACE OF SAID ENVELOPE, FIRST AND SECOND ACTUATING MEMBERSFASTENED TO SAID ENVELOPE ON OPPOSING SIDES OF SAID PASSAGEWAY, ANDMEANS FOR MOVING AT LEAST ONE OF SAID MEMBERS RELATIVE TO THE OTHER OFSAID MEMBERS BETWEEN FIRST AND SECOND POSITIONS, SAID MEMBERS IN SAIDFIRST POSITION BEING SPACED CLOSELY TOGETHER TO CONSTRICT SAIDPASSAGEWAY TO SEPARATE SAID FLUID INTO NON-CONTACTING